﻿/* Copyright 2010-present MongoDB Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

using System;
using MongoDB.Bson;
using MongoDB.Driver.Core.Misc;
using MongoDB.Driver.Linq.Linq3Implementation.Ast.Visitors;

namespace MongoDB.Driver.Linq.Linq3Implementation.Ast.Filters
{
    internal sealed class AstElemMatchFilterOperation : AstFilterOperation
    {
        private readonly AstFilter _filter; // note: using "@<elem>" to represent the implied element values

        public AstElemMatchFilterOperation(AstFilter filter)
        {
            Ensure.IsNotNull(filter, nameof(filter));
            Ensure.That(!filter.UsesExpr, "$elemMatch does not support $expr filters.", nameof(filter));
            _filter = filter;
        }

        public AstFilter Filter => _filter;
        public override AstNodeType NodeType => AstNodeType.ElemMatchFilterOperation;

        public override AstNode Accept(AstNodeVisitor visitor)
        {
            return visitor.VisitElemMatchFilterOperation(this);
        }

        public override BsonValue Render()
        {
            return new BsonDocument("$elemMatch", _filter.Render());
        }

        public AstElemMatchFilterOperation Update(AstFilter filter)
        {
            if (filter == _filter)
            {
                return this;
            }

            return new AstElemMatchFilterOperation(filter);
        }
    }
}
